


His Elder Brother

by raregloves



Category: Sherlock (TV)
Genre: Age Reversal, Daddy Issues, Hand Jobs, M/M, Mildly Dubious Consent, Older brother Sherlock, POV Mycroft Holmes, Set before ASIP, Sibling Incest, Somnophilia, Underage?? (Mycroft is 18), Younger brother Mycroft, dark!Sherlock
Language: English
Status: Completed
Published: 2014-06-22
Updated: 2014-06-22
Packaged: 2018-02-05 18:23:44
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 2,998
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/1827940
Author URL: https://archiveofourown.org/users/raregloves/pseuds/raregloves
Summary: <blockquote class="userstuff">
              <p>Mycroft is left in the care of his older brother Sherlock for a week.</p>
            </blockquote>





	His Elder Brother

**Author's Note:**

> Prompt: Holmescest, Role reversal. Sherlock as the older brother (same age diference).

Mycroft shifted uncomfortably on his brothers lounge, keenly aware of his parents sitting either side of him. Neither of them had chosen to notice his extreme discomfort, however. They were too focused Sherlock, who was pacing up and down in obvious anger. 

‘I don’t want him here,’ Sherlock was saying. ‘He’s eighteen, not five.’ 

‘Be that as it may,’ Father said, ‘we would like you to keep an eye on him while we’re gone. We’re not leaving him at home, not with the staff… it will only be for a week.’ 

‘I have a life,’ Sherlock snapped. ‘How has that not penetrated your thick skulls?’ 

‘But as you said, Sherlock, he’s not a five year old. It would be more like a flat-share than…’ 

Father tactfully didn’t say _babysitting_ but the word lingered, unspoken, in the air. 

‘Fine,’ Sherlock said, and Mycroft felt his stomach twist. He’d been expecting Sherlock to put up a longer fight, perhaps ask for money. ‘But he’d better not cause me any trouble or I’ll expect compensation.’ 

Ah, Mycroft thought, there it was. 

Father sighed but nodded, brushing invisible lint from the front of his suit jacket. Money was his comfort zone, something he could understand and appreciate in other people. To him, the idea that Sherlock might house his brother for a week merely out of the goodness of his heart was incomprehensible compared to Sherlock demanding money for time wasted. 

‘As you wish,’ Father said. ‘Mycroft will arrive in two weeks time at seven in the morning. And do stop scowling, Sherlock, I’m sure the two of you shall be fine. Come along, Violet, Mycroft.’ 

Father stood, taking Mother by the arm and giving Sherlock a brief nod before heading for the door. Mycroft followed them, but caught the look that Sherlock threw in his direction: pure and unhidden disgust.

 

~

 

The wheels of Mycrofts suitcase scraped against the concrete as he dragged it towards Sherlocks flat. Part of him wished he had gone to Russia. He hadn’t been invited (perhaps it was a romantic getaway?) and he didn’t particularly enjoy spending time with his parents. However the prospect of spending time with Sherlock held little joy either. 

The only sliver lining he could see was that he would be free to explore London on his own. Sherlock wouldn’t bother to take him anywhere, and probably wouldn’t ask where he went anyway. 

Mycroft came to Sherlocks door. His flat was not particularly nice. It smelt of the previous residents cat, had temperamental water pressure and had been decorated in Sherlocks distinctive style: scorch marks and taxidermy. 

He rang the bell and leaned against the wall, preparing himself for a long wait. He was not disappointed. He rang again in two minute intervals, occasionally giving a reassuring smile to concerned pedestrians.  

Internally he cursed his brother, leaving him to stand outside like a fool. Had he forgotten and gone out? Was he inside, sleeping? Or was he inside but busy- sex, drugs, acid on the table? Mycroft didn’t know enough about Sherlock to be sure.

So he passed the time by deducing strangers. Deducing was something Sherlock had taught him growing up, before he became wild and cruel. They were among Mycrofts favorite childhood memories. Deducing the children at the school and their parents, as well as all the teachers. Sherlock had always shown off, and gotten himself in trouble for it. Mycroft had never been like that, though. He had always been praised as the quiet one.

He hadn’t minded, though. Living in Sherlocks shadow meant he went unnoticed and often underestimated. 

The door flew open and Sherlock stood, baring the entry and glaring. He was bare footed and bare chested, wearing only a pair of ratty, dirty trousers. Mycroft stared. 

‘Well don’t just stand there staring,’ Sherlock said. ‘Get inside.’ 

Mycroft edged passed him, trying not to run his toes over with the suitcase. Once he was inside Sherlock slammed the door again and locked it, but left the key in the lock. 

His mind was still playing deducing, however- suddenly Mycroft could see Sherlock in a way he hadn’t been able to before. Didn’t use his money wisely, used his brain as a weapon, and he’d been right to assume drug use. He could see tiny injection marks running up the inside of Sherlocks left arm. 

‘The couch folds out into a bed so you’ll sleep on that,’ Sherlock said. ‘Make your own food and don’t go in my room. And don’t bother me. Those are the rules.’ 

‘Right,’ Mycroft said. He placed his suitcase by the lounge he’d sat on between his parents not so long ago. It didn’t look like it would turn out to be very comfortable.

Sherlock ignored him entirely, walking into the kitchen and rummaging around inside the cupboards. Mycroft watched him, and noticed at the same time that there was almost no food to be found. That would explain the prominence of Sherlocks ribs. 

‘Do you want me to buy food?’ Mycroft asked. ‘I’ve got money.’ 

‘What did I say about not bothering me?’ Sherlock snapped, not looking at him. ‘Ah!’ 

He had found what he was looking for- a jar containing something disgusting and clearly not edible. Mycroft thought it looked like a mixture of blood and animal hair. In fact it probably was. 

‘Tesco around the corner,’ Sherlock said, unexpectedly. ‘Though you could do with a little less feeding, if you ask me. Spare key is on the table somewhere.’ 

Mycroft flushed but said nothing. He opened his suitcase and found his wallet, tucked it into his pocket. The spare key was under a pile of newspapers. He slipped that into his pocket too and left, slamming the door behind him.

 

~

 

Over the next few days Mycroft discovered many things about living with his brother.

Sherlock didn’t sleep very often, and usually only for a few hours. He played the violin (loudly and often during the night) and seemed constantly on the edge of eviction due to the constant damage he inflicted upon the walls, floors and ceilings via his experiments. 

The amount of actual scientific theory involved in these experiments seemed limited to Mycroft. Sometimes Sherlock simply seemed to want to work out how best to annoy people, or how quickly it would take for fingernails to melt if placed in a microwave.

Most of the time, however, Sherlock was absent. He left the flat in a wide variety of outfits and returned hours later, sometimes in different clothes entirely. Mycroft didn’t say anything, but he was suspicious. Surely Sherlock couldn’t be playing numerous personas for legal reasons…

He tried to ignore that, however. His brother wasn’t going to ruin his time in London. Now he was free to do whatever he wanted he spent all his time moving about the city. He was particularly impressed by the sleek way the city worked.

The neatness of the sky scrapers, the cleanness of the glass, and in particular the grandeur of the older buildings, delighted him. The city seemed powerful to him, ancient, as if it was still remembering kings and wars even as double-decker tourism busses rushed by.

He visited parliament and a few of the banks and larger businesses, tall enough and (unlike Sherlock) well dressed enough not to attract undue attention. Here he found the power structures among the humans more fascinating than the architecture. Even without inside information on the people he observed he could deduce their secrets, the way they wielded different types of strength. 

Mycroft never saw Sherlock while he was out, deepening his suspicions that he was somewhere unsanitary and doing something illegal. But so far Sherlock hadn’t shown any signs of being high.

 

~

 

Approaching midnight on the third day of his stay, Sherlock emerged from his bedroom in tight jeans, joggers, a thick jacket from a university he didn’t attend and a fake nose ring. He barely glanced at Mycroft before leaving. 

Mycroft considered following him. The idea of catching Sherlock at whatever he was doing was extremely tempting, but he doubted he could pull it off. He wouldn’t look old enough, he didn’t have any appropriate clothes to change into, and he doubted that Sherlock would react well if he discovered his younger brother had started trailing him around London. 

However there might be another, safer way to catch Sherlock out…

He peered out the window but saw nothing. Sherlock would be gone for hours, and Mycroft wouldn’t touch anything. He’d never know.

He pushed open Sherlocks bedroom door and walked in, holding his breath, though he didn’t know exactly why. The bed was unmade (unsurprising) and feature of the room was the huge wardrobe: clothes were almost bursting from it, and lay discarded on the floor. Surely Sherlock couldn’t have this many alter egos? 

Mycroft could see expensive suits, fluorescent vests, leather trousers, a deep blue skirt, unwashed jackets, a McDonalds uniform, and a hard hat, amongst numerous other items.

His attention was drawn towards the desk in the corner. A large pile of files sat there, each covered in the handwriting Mycroft recognized from his childhood. He walked over, careful not to dislodge anything on the floor. 

Sherlocks papers. He saw numerous maps of London, both above and below ground. Certain areas were shaded in: red, blue, green. A few names were also included, though they meant nothing to Mycroft. ‘ _Angelo, brkn, restaurant opening soon_ ’ and _‘Victor, chapel, dog,_ ’ and ‘ _Lestrades old beat’._

But that wasn’t everything. Mycroft saw files on the homeless population, on various gay bars, on drug dealers… what on earth was Sherlock doing? Mycroft picked up a folder and flipped it open at random. 

_‘…found that the method of wearing them visibly only worked in combination with certain brands, and that these brands (see below) work as a nonverbal visual message. Furthermore fabric brightness-’_

A door slammed. Mycroft dropped the folder back on the desk and rushed out of Sherlocks room, slamming the door and running for the lounge. He made a running jump for it and landed with a huge thump. At once he began to snore. 

His acting was wasted, though. False alarm, Mycroft realized, just the wind blowing the bathroom door shut. Embarrassed by himself, Mycroft decided to stay on the lounge. It was late, after all.

 

~

 

Mycroft woke to a sharp pain in the side of his face and loud, confusing noise. He rolled over and fell from the lounge, hitting the floor awkwardly. Sunlight was coming in through the windows and Sherlock was standing over him, furious. 

‘Awake now?’ Sherlock snarled. ‘Good. Then you can explain why you were snooping through my room.’ 

‘I didn’t read anything.’ 

‘Oh, I see. Should I be thanking you?’ 

Mycroft got to his feet, refusing to be stood over and shouted at like a dog. He glared at Sherlock, who glared back unflinchingly. All his anger at the way Sherlock had treated him bubbled to the surface. 

‘You should,’ Mycroft said. ‘Nobody would’ve blamed me for trying to work out what on earth you’re doing with your life.’ 

‘My life is none of your business,’ Sherlock said. ‘I’m _babysitting you_ , not the other way around.’ 

‘Oh? Because I was under the impression you were incapable of buying your own food, or holding down a job. Funny.’ 

‘And what will you do, when you hold down your own job?’ Sherlock sneered, putting his face close to Mycrofts. ‘Follow in Fathers footsteps, messing around boring people for a living to get your hands on their money? How thrilling. What a good use of your time.’ 

‘Interesting lecture, coming from a junkie,’ Mycroft said, feeling a juvenile but heady rush of success. ‘Don’t think I don’t know.’ 

‘Very clever, Mycroft,’ Sherlock said. ‘You have working eyes, how clever of you! Have you deduced why you dress like a forty year old man yet, too? No? Oh, let me be the one to inform you…’ 

Sherlock put his hands on Mycrofts shoulders, their faces still uncomfortably close. His wild blue eyes were alight with vindictive joy. 

‘When you were here before with darling Father and darling Mother you didn’t say a single word, did you? Even though you were uncomfortable, even though we were talking about you. And do you want to know why that is? Because Father thinks if he raises you differently, you won’t turn out like me. So now look at you. Can’t stand up for yourself because of scary big brother Sherlock, can’t pick your own clothes because Father does that for you, can’t speak your mind because you might upset Mummy. You are a chubby, feeble-minded, cheap version of Fathers ideal son. Understand?’ 

Sherlock let him go with a shake. Mycroft stumbled backwards until his legs hit the lounge. He sat, stunned, as Sherlock left the flat again.

 

~

 

Mycroft spent the rest of the day in a kind of haze. He walked through London, unable to stay in Sherlocks flat, hardly aware of the people he bumped into as he walked. 

Various emotions battled for dominance. Denial, anger, shame, hatred, shock… but he didn’t even know who to direct the emotions towards. Himself? Sherlock? Their father?

‘Watch it, kiddo,’ a man said, as Mycroft walked directly into him. ‘Watch where you’re going.’

 

~

 

The flat was empty when Mycroft returned. He ate an apple, unable to face cooking an actual meal in Sherlocks kitchen.

The issue, Mycroft knew, was that Sherlock was right about him. His parents had never understood Sherlock and, with Mycroft, had attempted to raise a child they would understand: a child more like them, who did what they expected him to do.

Mycroft looked in Sherlocks bathroom mirror, taking in his Fathers pointed nose and slim lips. In his neat, rather formal clothing he could have passed for a miniature version of him. 

Furious, Mycroft stripped off his clothing and went into Sherlocks room with an air of defiance, picking out a pair of dirty jeans and a large, comfortable looking shirt. This time, when he looked at his reflection, he hated himself a little less.

 

~

 

Sherlock returned the next day, still in the clothes he’d worn when he confronted Mycroft. 

Mycroft was on the lounge, half-asleep. He watched Sherlock walk through the flat and the pause at the sight of Mycroft in his clothes. But he didn’t explode. Instead he smiled before vanishing into the bathroom. Mycroft sighed, feeling oddly relieved. 

He heard the shower start up. He wondered if Sherlock would talk to him more, now that things were changing… if things were changing… 

Mycroft drifted in that peaceful state between resting and awake. 

The shower stopped, and the bathroom door opened. He heard Sherlock cross behind the lounge, and his bedroom door close. Previously he’d tried to ignore Sherlock as he moved around, had tried to maintain the illusion of a flat-share. Now, though, he felt a keen awareness of where Sherlock was, of what he was doing. 

Sherlock emerged from his bedroom fully dressed, his hair still wet. He came to stand in front of the lounge, peering down at Mycroft with an unreadable expression on his face. 

‘Look at this,’ Sherlock said softly. ‘All dressed up but nowhere to go. I’m glad you listened to me, Mycroft. You’re already looking less pathetic.’ 

Mycroft smiled, unwilling to sit up. He was so tired. Not much had happened, and yet he felt as though he’d been on a long journey. Surely Sherlock would understand that, and let him have a nap.’ 

‘So tired,’ Sherlock said, as if hearing his thoughts. ‘Let me put you to sleep.’ 

He crouched down in front of Mycroft and began to stroke his hair. Sherlock had long, gentle fingers. Mycroft let his eyes close as Sherlock slid his fingers through his hair. It was a soothing sensation. 

‘Exactly,’ Sherlock said. ‘Relax now.’ 

Sherlocks hand ran over the side of his face, his hand warm and interestingly calloused. Violinist fingers, Mycroft thought to himself vaguely. He had no memory of being touched like this. 

‘Ok?’ Sherlock said, his hands running down Mycrofts chest now. ‘Ok?’ 

‘Mmmhmm,’ Mycroft mumbled, too exhausted to reply properly. 

Sherlocks hands pushed his shirt up over his stomach. The sensation of his hands sliding over his skin was strange, intimate. Half ticklish, half uncomfortable, and curiously stimulating. Mycroft exhaled. 

Erections were just a typical male reaction to physical stimulation, after all. He didn’t need to be embarrassed around Sherlock. Sherlock would understand. Yes, it would be fine.

He felt his cock thicken as Sherlock rubbed him, his fingertips sometimes circling his nipples. Mycroft felt almost as if he were dreaming. 

Sherlocks hand slipped lower and Mycroft jumped a little at the feeling of a large, warm hand around his cock. He could hear Sherlock breathing. It felt amazing, too- the soft skin of Sherlocks palm, the way the pads of Sherlocks fingers ran over his slit. Christ. Mycroft opened his mouth, abruptly breathless. 

‘Come on, Mycroft,’ Sherlock said. ‘I got you now.’ 

Sherlocks hand tightened, sped up: Mycroft began to hyperventilate, though he didn’t feel as if he were waking up, didn’t feel as if it were really happening. It all seemed like some hot, impossible dream. His balls were drawing up towards his body, his skin felt hot, almost tingly. 

‘Let go for me, Mycroft,’ Sherlock said, his voice barely above a whisper. ‘I’ll take care of you, I will…’ 

Mycroft came in his pants, his entire body shaking on the lounge, Sherlocks hand still wrapped around him, pulling and pulling until he was soft again. He felt soft waves of hot, sweet pleasure move through him, unwinding every tightened muscle in his body. 

‘Perfect, Mycroft,’ he heard Sherlock say, through his exhaustion and arousal. ‘You were so good for me, you’re so good…’ 

A feeling of contentment was sweeping over him. He’d never felt so relaxed in his life.

‘Sleep,’ Sherlock murmured, voice low and soothing. ‘Sleep now, Mycroft…’

**Author's Note:**

> You can send me a prompt on my tumblr- I love rare pair fic :)
> 
> raregloves.tumblr.com


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